1. Field of the Invention
The present invention relates to a lighttight package of a rolled light-sensitive material.
2. Description of the Prior Art
In the packaging of light-sensitive material for use in e.g. phototypesetters or X-ray imagers, disposable film roll cassettes as well as daylight loading film roll packages are used. Daylight loading film packages are cheaper than disposable film cassettes, and are also preferred for ecological reasons.
Several types of daylight loading film roll packages are known that comprise a circumferential wrapper and two end covers lighttightly sealed to the circumferential cover. In one embodiment, the circumferential wrapper has lips that are folded over the end covers and are sealed thereto (see U.S. Pat. No. 4,505,387 of Fuji Photo Film Co., Ltd.) In another embodiment the end covers have lips that are folded over the circumferential cover and are sealed thereto (see U.S. Pat. No. 4,148,395 of E.Kodak Cy.) In still another embodiment marginal portions of the circumferential and the end covers are sealed to each other at their inside faces (see U.S. Pat. No. 4,733,777 of Agfa-Gevaert N. V.) These, and similar packages have the advantage that their length is neglectably larger than the width of an unwrapped film roll so that their use in so-called machine-dedicated cassettes that are originally designed for being loaded in a darkroom with a roll of unwrapped film, does not raise problems. However, sealing the circumferential wrapper to the end covers at the respective marginal zones requires a great precision in the location of the respective elements in order to obtain a light-proof seal.
Other types of daylight loading film packages are known that comprise two flanges at opposite ends of a core and a circumferential wrapper sealed to the peripheral edge of the flanges. The flanges must have a substantial thickness to obtain a sufficiently strong seal. An example of suchlike package is disclosed in EP-A-03 26 260 of Sony Corp. A similar daylight loading film package with two end discs is disclosed in DE 41 33 530 C1 of Du Pont de Nemours GmbH, DE. This latter invention involves the use of end discs with an annular recess at their outside faces and of a flexible circumferential wrapper that is tensioned during its winding around the wound film roll so that its lateral, free margins will shrink and fold, and become seated in wrinkled form in the annular recesses of the flanges. The light-tightness of this package leaves much to be desire since the wrinkled margins inevitably have overlapping portions, the overlying areas of which cannot be in contact with the end disc and results in direct access by rays of incident light to the any gaps between the faces of the end discs and the wrapper tensioned thereover. If, for one reason or another, this tension is locally unsufficient to ensure good contact, light may reach the photographic material and cause fogging.